1. Field of the Invention
The present invention relates to integrated circuit packaging technology, and more particularly, to electrostatic discharge protection for integrated circuits.
2. Background Art
Integrated circuit (IC) chips or dies from semiconductor wafers are typically interfaced with other circuits using a package that can be attached to a printed circuit board (PCB). One such type of IC die package is a ball grid array (BGA) package. BGA packages provide for smaller footprints than many other package solutions available today. A BGA package has an array of solder ball pads located on a bottom external surface of a package substrate. Solder balls are attached to the solder ball pads. The solder balls are reflowed to attach the package to the PCB.
Millions of BGA packages are manufactured each year for implementation in electronic devices according to increasingly finer fabrication technologies, including 90 nm and 65 nm technologies. Such BGA packages undergo rigorous testing during various phases of their design and/or assembly processes. For example, customers may require that a particular BGA package design pass electrostatic discharge (ESD) protection testing. Such ESD testing is performed to determine that the integrated circuit of the BGA package is not damaged by an electrostatic discharge of a particular test discharge amount. It is desirable to perform the ESD protection testing with the BGA package attached to the circuit board designed to mount the BGA package in a commercial product. This is because electrical characteristics of the BGA package are altered when mounted to the circuit board, thereby altering the ESD sensitivity. Thus, an ESD test performed on the BGA package when attached to the circuit board is a more representative test.
However, in some situations, it may not be practical to perform the ESD testing with the BGA package mounted to the circuit board. For example, the circuit board may not yet be designed, the circuit board may not be available to the BGA package manufacturer, and/or further reasons may make such ESD testing impractical. Thus, in some situations, it may not be possible or practical to perform ESD testing of a BGA package in a manner that verifies ESD protection for the package in its actual operating environment.
Therefore, what are needed are ways of performing ESD testing on a BGA package in a manner similar to its actual operating environment.